The present invention relates in general to an image signal reproduction circuit for a solid-state image sensor and, more particularly, to a reproduction circuit device for reproducing an output image signal produced by a solid-state image sensor, which senses an image while swinging relative to an incoming image light.
U.S. patent application Ser. No. 451,465 (Nozomu HARADA et al) discloses a technique for producing an image of high resolution, the degree exceeding the actual number of picture elements, by employing a solid-state image sensor having a limited number of picture elements. Typically, a solid-state image sensor is arranged so as to vibrate or swing in a plane orthogonal to an incoming image light, horizontally, periodically and relative to the image light in a given vibration mode. When the sensor is applied for an NTSC television system in which one form is comprised of two fields, the image sensor swings so that it senses an image at different sampling positions during the one field period. As a result, a reproduced picture has an enhanced resolution, which is obtained as if the picture element members of the image sensor per se were doubled.
An image signal obtained by such a swing-type solid-state image sensor normally includes a reset noise component (e.g., approx. 500 mV) and a DC offset component (e.g., approx. 5 V to 10 V). Therefore, it is necessary to reproduce an image of preferable quality that the output signal from the solid-state image sensor is processed in such a manner that the noise components are removed without causing the waveform deterioration of the rectangular image signal components. An arrangement for preferably removing the noise components is by using a linear detection circuit. However, the production of this circuit is commercially difficult. In order to process a signal without deteriorating the image signal component in a case where the frequency f.sub.cp of a clock pulse of the solid-state image sensor is 7.16 MHz, it is necessary to pass tertiary high frequency components contained in the signal; the result being that the frequency band of the linear detection circuit requires at least 20 MHz or more. In the detection circuit having a wide frequency band, the deterioration of the signal phase characteristics cannot be avoided. As a result, a problem arises such that an amplitude distortion is generated between the image signals occurring in both fields, thereby producing a flicker.